A take-up spool latch for a seat belt retractor of the type comprising a spool journalled for rotation in a spool frame and incorporating a torsion spring for retracting a seat belt, the latch having a clutch member and a brake member with means between them limiting relative movement, both the clutch and brake members having cam surfaces thereon which are engaged by a pawl which co-operates with a ratchet on the spool and is so arranged that:
A. upon retraction of a seat belt which has been withdrawn from the spool the cam surfaces retain the pawl out of engagement from the ratchet teeth,
B. upon initial further withdrawal and during the limited rotation between the brake and clutch member the pawl is released by the cam surfaces and engage the ratchet teeth thereby preventing retraction,
C. upon still further withdrawal the cam surfaces again engage the pawl and retain it out of engagement from the ratchet teeth, so that full retraction can again take place.
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14. In a seat belt retractor having a seat belt carried on a spool, a torsion imparting spring arranged for retracting the belt on the spool and an emergency locking means for preventing belt withdrawal upon sudden change in vehicle inertia, a take-up spool latch means for relieving tension on the belt when withdrawn from the spool and placed in use which acts independently of said emergency locking means, comprising:
ratchet means associated with said spool and having ratchet teeth inclined in a direction to prevent retraction of said spool; pawl means engageable with said ratchet teeth; and means frictionally driven by said spool for holding said pawl means out of engagement with said ratchet teeth during retraction of said belt on said spool and for allowing said pawl means to engage said teeth in response to spool rotation imparted by a retraction movement of a withdrawn seat belt followed by a subsequent limited further withdrawal movement of said belt said frictionally driven means including means for causing said pawl means to release said ratchet means and allow retraction of said belt on said spool automatically by the urging of said torsion imparting spring upon a still further withdrawal movement of said belt beyond said limited further withdrawal of said belt.
18. In a seat belt retractor having a seat belt carried on a take-up spool which is rotatable in a frame, a spool retracting spring for normally biasing said spool in a belt-retracting direction and thereby normally imparting tension to the seat belt when it is placed in use, the improvement comprising:
pawl and ratchet means operatively interconnecting said frame and spool for preventing retraction of said belt under urging of said spring, a clutch member driven by said spool; a brake member driven by said clutch member with means for allowing limited relative movement therebetween; and cam means on both said members for selectively locating the pawl in operative and inoperative positions, each said member having first and second positions, the cam means being such that if either one or the other or both of said members are in said first positions said pawl is located in said inoperative position and when both said members are in said second positions said pawl is located in said operative position, and wherein spool rotation in response to retraction movement of a withdrawn belt moves said brake member to said second position and said clutch member to said first position, subsequent spool rotation in response to further belt withdrawal moves said clutch member relative to said brake member to said second position, whereby said pawl is operated to prevent belt rotation.
11. In a seat belt retractor having a spool frame, a spool journalled for rotation in the spool frame, and a torsion imparting spring operably connected between the spool and the spool frame arranged for retracting a belt when carried on the spool, a take-up spool latch comprising:
a clutch member journalled for rotation relative to the spool, a brake member journalled for rotation relative to both the spool and clutch member, drive means between the clutch member, spool and brake member, interengaging means between the clutch member and brake member limiting relative rotation therebetween, cam surfaces on both the clutch and brake members, a ratchet having teeth on the spool, a pawl, pivot means on the spool frame supporting the pawl for pivotal movement, cam engaging means coupled to the pawl and engaging the cam surfaces of both the clutch and brake members so that the pawl is pivoted into or out of engagement with the ratchet teeth upon rotational movement of the clutch and brake members, such that: a. upon retraction of a seat belt which has been withdrawn from the spool, the pawl is out of engagement with the ratchet teeth, b. upon initial further withdrawal and during said relative rotation between the clutch and brake members, the pawl pivots into engagement with the ratchet teeth thereby preventing retraction, and c. upon further withdrawal the cam surfaces again pivot the pawl out of engagement with the ratchet teeth. 1. In a seat belt retractor having a spool frame, a spool journalled for rotation in the spool frame, and a torsion imparting spring operably connected between the spool and the spool frame arranged for retracting a belt when carried on the spool, a take-up spool latch comprising:
a clutch member coaxial with the spool and in frictional engagement with the spool, a brake member coaxial and rotatable with respect to the spool and in frictional engagement with the spool frame, interengaging means between the clutch and brake members limiting relative rotation therebetween, cam surfaces on both the clutch member and the brake member, a ratchet having ratchet teeth on the spool, and a pawl pivoted to the spool frame for engaging the cam surfaces of both the clutch and brake members and the ratchet teeth, the cam surfaces controlling the engagement of the pawl with the ratchet teeth such that: a. upon retraction of a seat belt which has been withdrawn from the spool, the cam surfaces pivot the pawl out of engagement with the ratchet teeth, b. upon initial further withdrawal and during said limited relative rotation between the clutch and brake members, the pawl is released by the cam surfaces and pivots to engage the ratchet teeth thereby preventing retraction, and c. upon further withdrawal to and beyond said limited relative rotation accomplished by the interengaging means, the cam surfaces again engage the pawl and pivot it out of engagement with the ratchet teeth. 16. In a seat belt retractor having a spool frame, a spool journalled for rotation in the spool frame, and a torsion imparting spring operably connected between the spool and the spool frame arranged for retracting a belt when carried on the spool, a take-up spool latch means comprising:
a clutch member frictionally driven by said spool and having a first cam surface; a brake member driven by said clutch member, interengaging means between said members allowing only limited relative rotation therebetween, said brake member having a second cam surface; a retraction preventing ratchet and pawl means associated with said spool and cam surfaces for selectively preventing retraction of said spool on alignment of said members in predetermined manner relative to said ratchet and pawl means; and means for mounting said members for limited movements under the drive of said spool for bringing said members into said alignment in response to spool rotation imparted by a retraction movement of a withdrawn belt followed by a subsequent limited further withdrawal movement of said belt
thereby engaging said pawl means with said ratchet. 17. In a seat belt retractor having a seat belt carried upon a take-up spool, a spool retracting spring for normally biasing said spool in a belt retracting direction and thereby normally imparting tension to the seat belt when it is placed in use, and a spool locking means for locking the spool against belt withdrawal under emergency conditions, the improvement comprising the provision of: pawl and ratchet means associated with said spool independent of said spool locking means for preventing retraction of said belt under urging of said spring; and means driven by rotation of said spool for operating said pawl and ratchet means to prevent belt retraction under urging of said spring in response to spool rotation imparted by a retraction movement of a withdrawn belt followed by a subsequent further limited withdrawal movement of said belt, said driven means including means for de-activating said pawl and ratchet means to allow retraction of said spool under the urging of said spring in response to a still further withdrawal movement of said belt beyond said limited withdrawal of said belt. 7. In a seat belt retractor having a spool frame, a spool journalled for rotation in the spool frame, and a torsion imparting spring operably connected between the spool and the spool frame arranged for retracting a belt when carried on the spool, a take up spool latch comprising:
a clutch disc and a brake disc both coaxial and rotatable with respect to the spool, a spring between said discs urging the clutch disc into frictional engagement with the spool and the brake disc into frictional engagement with the spool frame, interengaging means between the brake disc and the spool frame limiting rotary movement of the brake disc, a radially inwardly extending pawl recess in the periphery of the brake disc, a radially inwardly extending recess in the periphery of the clutch disc of greater circumferential length than the pawl recess, said peripheries and recesses forming co-operating cam surfaces, a spigot outstanding from a face of one of the discs, and co-operable limit means on the other disc engageable by the spigot to thereby limit relative rotation of discs to a degree exceeding said limited rotary movement of the brake disc, a ratchet having ratchet teeth on the spool, a pawl pivoted on the spool frame arranged to engage the ratchet teeth and also to engage the cam surfaces, the inter-relation of said interengaging means, cam-forming recesses and limit means being so arranged that: a. upon retraction of a seat belt which has been withdrawn from the spool, the clutch disc is urged to rotate owing to said frictional engagement with the spool and the brake disc is urged by the spigot to rotate, whereby the pawl recess moves into alignment with the pawl but the cam surface of the clutch disc pivots the pawl out of engagement with the ratchet teeth, b. upon initial further withdrawal of the seat belt from the spool and during said limited relative rotation between said clutch and brake discs the clutch disc is urged to rotate in a reverse direction to place its radially inwardly extending recess into alignment with the pawl, whereby the pawl pivots to engage the teeth of the ratchet, and, c. upon further withdrawal beyond the limit of said limited relative rotation of the discs, the spigot of the clutch disc imparts rotation to the brake disc and the cam surface of the brake disc lifts and pivots the pawl out of engagement with the ratchet teeth. 2. A take up spool according to
3. A take up spool according to
4. A take up spool according to
5. A take up spool according to
6. A take up spool according to
8. A take up spool lug according to
9. A take up spool lug according to
a clutch member journalled for rotation relative to the spool, a brake member journalled for rotation relative to both the spool and clutch member, drive means between the clutch member, spool and brake member, interengaging means between the clutch member and brake member limiting relative rotation therebetween, cam surfaces on both the clutch and brake members, a ratchet, having teeth, on the spool, a pawl carried by and movable with respect to the spool frame for engaging the ratchet teeth, and cam engaging means coupled to the pawl and engaging the cam surfaces of both the clutch and brake members, the cam surfaces controlling the engagement of the pawl with the ratchet teeth such that: a. upon retraction of a seat belt which has been withdrawn from the spool at least one of the cam surfaces engages the cam engaging means and holds the pawl out of engagement with the ratchet teeth, b. upon initial further withdrawal spool rotation causes cam movement which in turn allows the pawl to engage the ratchet teeth thereby preventing retraction, and c. said cam surfaces of the clutch and brake members co-operate to move and to hold the pawl out of engagement with the ratchet teeth during further withdrawal and subsequent retraction. 12. A take-up spool latch according to
13. A take-up spool latch according to
15. The take-up spool latch means of
a clutch member frictionally driven by said spool and having a first cam surface engaging said pawl means, said first cam surface including a clutch recess therein; a brake member having a second cam surface engaging said pawl means, said second cam surface including a brake recess therein; interengaging means between said members allowing limited relative rotation therebetween but otherwise effecting concurrent rotation; whereby after withdrawal of a seat belt on said spool said retraction movement of said belt moves one of said members into a position where its recess is in alignment with said pawl means and said subsequent limited further withdrawal movement of said belt moves the other of said members relative to the first said member to place said recess of the other said member also in alignment with said pawl means allowing said pawl means to engage said ratchet teeth.
19. The improvement in seat belt retractor of
friction means are provided in association with said clutch member for driving it off of frictional contact with a portion of said spool.
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This invention relates to a spool latch which is functional to restrict take-up of a spring return seat belt, in such a way as to allow a small degree of freedom of movement wherein the retracting spring is restrained from imparting tension to the seat belt.
The invention relates to seat belt spools of any one of several types. It is applicable to the type of spool described and illustrated in Australian Pat. No. 273,896 issued to Teleflex Products Limited, a British company, wherein an internal ratchet is engaged by a centrifugally operable pawl which arrests rotation of a spool upon sudden extension of a seat belt. This type of spool is known as a "body sensitive" spool, that is, it locks when the body of a wearer is suddenly thrown forwardly.
This invention is also applicable to the type of spool known as a "vehicle sensitive" spool. Such spools are described in U.S. Pat. No. 3,578,260. The invention is still further applicable to locking retractors.
As far as is known to the applicants, there is no related art with respect to mechanism which will allow a small degree of freedom of movement wherein the retracting spring is restrained from imparting tension to the seat belt.
In a motor vehicle, if a retractor is used wherein a seat belt will have a continually applied retractor force, the pressure of the belt against the wearer may result in discomfort, and it has been found desirable for the wearer to have the belt at a station which is other than its retracted position but have a small degree of freedom of movement beyond the station, wherein the seat belt is not under tension.
In general terms the invention includes a clutch member and a brake member both of which are coaxial with the spool and are respectively in frictional engagement with the spool and the spool housing, there also being frictional engagement means between the two members. The two members also have interengaging means which limit relative rotation therebetween, and each member is provided with a cam surface. The two cam surfaces control movement of a pawl which is pivoted to the spool frame and which is either in engagement with a ratchet on the spool so as to limit retraction of the spool or lifted out of engagement with the teeth of the ratchet by the cam surfaces so that the spool is free to rotate in either direction. The interengaging means between the clutch and brake members are so arranged in conjunction with the cam surfaces that when a seat belt inTo facilitate understanding the operation of the clutch and brake members, they are drawn in the opposite hand in FIGS. 8, 9 and 10, that is viewed from the brake member end. 53 55 of a side wall of the frame 12. The effective mean radius of the clutch disc friction pad 35 is greater than the effective mean radius of the friction pad 37 on the brake disc, so that the clutch disc 30, although being capable of slipping against the spool will not slip until after the brake disc 31 has slipped and been arrested. The mean diameter of the Belleville spring washer 32 is less than that of the friction pad 37 on the brake disc, and the spring washer 32 does not transfer sufficient torque to rotate the brake disc 31.
Integral with the bush 29 and the primary ratchet plate 21 is a ratchet disc 40, the ratchet disc 40 having teeth inclined in such a direction as to prevent retraction of a seat belt. (see FIG. 2)
A double lobed pawl 41 is pivoted to the outer wall of the spool frame 12, one lobe 42 of the double lobed pawl 41 engaging the teeth of the ratchet disc 40 and the other lobe 43 extending across the peripheral edges of the two discoid members 30 and 31.
The clutch disc 30 is provided with a cam surface comprising a circumferentially extending radial recess 46, which for simplicity is termed herein "clutch recess" while the brake disc 31 is also provided with a cam surface comprising a circumferentially extending recess 47 (herein called "brake recess") in its periphery, and a pawl recess 48 circumferentially spaced from the brake recess 47. One end of the pawl recess 48 terminates in a wall 49 which is inclined to the radial.
Disposed between the clutch disc 30 and the brake disc 31 is an interengaging means for limiting relative rotation therebetween.
The clutch disc 30 has a projecting circular section spigot 52 (herein called "clutch spigot") which, upon assembly, is movable within and interengages the brake recess 47. Disposed further between the brake disc 31 and the spool frame 12 is means for limiting the rotary movement of the brake disc 31. Brake disc 31 has an outstanding lug 53 (herein called "brake lug") which is movable within and interengages an arcuate slot 54 in the side wall of the spool frame 12.
The function is briefly as follows.
Upon initial withdrawal of the seat belt from either its retracted position or from any other station the clutch disc 30 is rotated by frictional inter-connection with the spool 13 and allows the inner pawl lobe 43 to fall into the now aligning clutch recess 46 and "pawl recess" 48 (which are of similar diameter) and so allows the outer pawl lobe 42 to engage the ratchet teeth. At this stage retraction would be prevented, this stage being illustrated in FIG. 8. Further withdrawal will continue to rotate the clutch disc 30 only in an anticlockwise direction as shown in FIG. 8 until the clutch spigot 52 abuts the end of the brake recess 47. To this point the angular length of the clutch recess 46 allows continued engagement of the pawl 41 with the teeth of the ratchet disc 40 and retraction is incrementally prevented. Continued withdrawal rotates the brake disc 31 together with the clutch disc 30 by interengagement between the clutch spigot 52 and the brake recess 47 until the brake disc 31 is brought to a halt by the brake lug 53 traversing and abutting the end of the "arcuate slot" 54. This small rotation of the brake disc 31 brings the inclined wall 49 of the pawl recess 48 under the inner lobe 43 of the pawl 41 and lifts the pawl to disengage with the ratchet teeth, which will now allow retraction. Still further withdrawal will cause slippage between the spool and the clutch disc but limited or complete retraction is still possible. This stage is illustrated in FIG. 9.
During the first stage of retraction the clutch disc 30 is rotated back by its frictional inter-connection with the spool 13 to the limit of the travel of the clutch spigot 52 in the brake recess 47 and brings the clutch recess 46 and the pawl recess 48 into mis-alignment which continues to hold the pawl 41 disengaged from the teeth of the ratchet disc 40. Further retraction will rotate both the brake disc 31 and the clutch disc 30 to the limit of travel of the brake lug 53 in the arcuate slot 54 and so bring the pawl recess 48 again into alignment with the inner lobe 43 of the pawl 41. However, the pawl 41 is now prevented from engaging the ratchet teeth by the outer peripheral edge of the clutch disc 30, at the end of the clutch recess 46. This is illustrated in FIG. 10.
During further retraction slippage occurs between the clutch disc 30 and the spool 13 under the effect of the torsion spring 14.
However, upon arresting of the retraction of the belt (due, for example, to the belt engaging the body of the user) rotation ceases, and slight forward movement of the user will cause the clutch disc 30 to move in a direction such that the clutch recess 46 again aligns with the pawl recess 48, the inner lobe 43 of the pawl 41 is no longer prevented from dropping and the outer lobe 42 is then allowed to drop to engage the teeth of the ratchet disc 40. This then gives the user an opportunity to relax the tension of the belt without losing any of its safety features.
The pawl 41 has been described as functioning under the effects of gravity but it will be clear to those skilled in the art that use of a light spring may be made, if required. The operative mechanism has been described with respect to a pair of discs, but their equivalents (for example, conical or cylindrical members) may be used if this is desired.
| Patent | Priority | Assignee | Title |
| 4386744, | Mar 16 1981 | TRW Vehicle Safety Systems Inc | Comfort mechanism for safety belt retractors |
| 4553716, | Feb 24 1982 | REPA Feinstanzwerk GmbH | Mechanism in roll-up device for safety belts in motor vehicles |
| 4760975, | Jun 30 1987 | OCCUPANT SAFETY SYSTEMS, INC , A DE CORP | Seat belt retractor |
| Patent | Priority | Assignee | Title |
| 3430891, | |||
| 3491966, | |||
| 3550875, | |||
| 3578260, | |||
| 3598335, | |||
| 3664599, | |||
| 3682412, | |||
| FR986,867, |
| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| May 05 1975 | Rainsfords Metal Products Proprietary Ltd. | (assignment on the face of the patent) | / |
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